Nearshore Berm Performance at Newport Beach, California, USA

Mesa, Chuck

doi:10.1061/9780784402429.361

Cited by 2 publications

(3 citation statements)

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“…The berm was considered moderately active, because the berm crest eroded, and the material was transported shoreward. However, the berm's centroid remained fairly stable (Mesa 1996).…”

Section: Sand Island Alabama (1987)mentioning

confidence: 96%

Evaluation Techniques for the Beneficial Use of Dredged Sediment Placed in the Nearshore

McFall

Brutsche

Priestas

et al. 2021

J. Waterway, Port, Coastal, Ocean Eng.

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Maintaining navigable waterways through dredging is vital to society and the economy, especially as global transport and cargo loads increase. Decision makers require rapid techniques to evaluate potential placement alternatives for the dredged sediment. When appropriate, dredged sediment can be placed in the nearshore as a berm or a mound, often with the expectations of dissipating wave energy further offshore and inducing shoreward sediment transport. However, the exact placement area requires the water depth, hydrodynamic climate, and sediment size to be considered. Previous work used the well-known depth of closure concept to assess berm stability. A web-based Sediment Mobility Tool (SMT) was recently developed to assess the probability of sediment transport and direction with the knowledge of a few simple parameters. In this study, 20 historical projects that placed dredged sediment in the nearshore are reviewed to evaluate the depth of closure equations predictive capability on berm stability. The frequency of sediment mobilization and cross-shore transport direction are estimated for nine historical projects. The evaluated projects represent a diverse range of construction methods, placement geometries, sediment characteristics, and wave climates. The techniques used to estimate sediment mobilization frequency and transport direction are universal. These techniques are an essential step for engineers and planners to evaluate the potential volumes of dredged material that nearshore placement operations might yield to nourish a beach profile.

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“…The berm was considered moderately active, because the berm crest eroded, and the material was transported shoreward. However, the berm's centroid remained fairly stable (Mesa 1996).…”

Section: Sand Island Alabama (1987)mentioning

confidence: 96%

Evaluation Techniques for the Beneficial Use of Dredged Sediment Placed in the Nearshore

McFall

Brutsche

Priestas

et al. 2021

J. Waterway, Port, Coastal, Ocean Eng.

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“…Newport Beach, California: The nearshore berm at Newport Beach was constructed in October 1992 as a series of irregular mounds spanning a 900-m length of beach. The sediment was placed between the 4 and 9 m depth contours (relative to MSL), with its crest approximately 400 m offshore and h crest = 4.5 m at placement (Mesa 1996). Because the survey area from the original site report extends outside the initial berm footprint, the deflation rate for Newport Beach was recalculated for this study to ensure that the value was specific to the control volume of interest.…”

Section: Cross-shore Transport Calculationsmentioning

confidence: 99%

“…Because the survey area from the original site report extends outside the initial berm footprint, the deflation rate for Newport Beach was recalculated for this study to ensure that the value was specific to the control volume of interest. Using the time series of bathymetric profiles in Mesa's (1996) Newport Beach report, the deflation rate was calculated from the initial placement volume of 9.8 × 10 5 m 3 and an apparent 28% reduction in the berm's vertical cross-sectional area over the 2.5-year monitoring duration. The local WIS hindcast records a bimodal distribution of T p with peaks at 7 and 15 s and a maximum period of 24 s. The average of H 0 was 0.8 m with a maximum of 3.9 m. Few waves are predicted to break within the placement boundaries.…”

Section: Cross-shore Transport Calculationsmentioning

confidence: 99%

Evaluating Transport Formulations for Application to Nearshore Berms

Bain

McFall

Krafft

et al. 2021

J. Waterway, Port, Coastal, Ocean Eng.

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Dredged sediment is commonly placed as a submerged nearshore berm to nourish the beach or to dissipate high-energy waves, but the lifespan of such features is not easily predicted by existing methods. This paper presents a simple technique for generating order-of-magnitude estimates of the sediment transport rate of nearshore berms using offshore hindcast wave characteristics transformed to the nearshore. Total longshore transport for the entire nearshore region is calculated using eight published longshore transport equations (e.g., CERC equation and Kamphuis equation), which were evaluated for their relative performance. Because nearshore placements occupy only a portion of the crossshore profile, the total longshore transport rate is scaled by an empirically-based fraction between 0 and 1, which is determined by the nearshore berm's position in nondimensional space. The cross-shore transport rate is calculated independently using the near-bed orbital velocity from stream-function wave theory. The longshore and cross-shore transport rates are then superimposed to generate a total transport rate for the nearshore berm's constructed footprint. The total transport rates were calculated at 11 historical nearshore berms and evaluated based on accuracy, inclusion of relevant coastal processes, and sensitivity to input parameters. The recommended total transport rate technique resulted in an average percent error magnitude of 72% and a maximum percent error magnitude of 167% at the historical placement locations. This technique is recommended for generating rapid, order-of-magnitude estimates of nearshore berm deflation rates for project design, particularly in scenarios when application of a full numerical model is prohibitive.

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Nearshore Berm Performance at Newport Beach, California, USA

Cited by 2 publications

References 0 publications

Evaluation Techniques for the Beneficial Use of Dredged Sediment Placed in the Nearshore

Evaluation Techniques for the Beneficial Use of Dredged Sediment Placed in the Nearshore

Evaluating Transport Formulations for Application to Nearshore Berms

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